Median filters having modules for receiving the current value of an incoming digital signal

Abstract

A median filter includes a number of identical modules each arranged simultaneously to receive the current value of an imcoming digital signal. Each module includes a feedback shift register of special design enabling it to be set to receive its input to any one of its stages. The shift registers of the different modules are set to receive their inputs at different stages and logic means is associated with each shift register for comparing the content of one stage with the contents of each other stage to determine whether the content of that said one stage is the medium value. If it is the median value it is passed to an output of the circuit.

I claim: 
     
       1. A median filter comprising a plurality of identical modules each arranged to simultaneously receive the current value of an incoming digital signal, each module comprising a feedback shift register which is capable of being set to receive an input signal at any one of its stage, means for setting the feedback shift register of each module to receive an input signal at a stage different than that of the other shift registers, means for comparing the content of one stage of each of said feedback shift registers with the content of each other stage of said feedback shift register to determine whether the content of said stage is the median value, and for passing the content of said one stage to the output in response to such detection of said median value. 
     
     
       2. A median filter according to claim 1 wherein said means for setting each of said feedback shift registers comprises a selector for each stage of said shift register for feeding to said stage the content of a previous stage of the input signal and means for setting the selector so that said input signal is passed through a chosen one of the stages so that each of the other stages receivers the output from the previous stage.